1. Field of the Invention
The present invention relates to the physical connections and architecture of electronic circuits and more particularly, to in-line memory modules and matching sockets for use in computer systems.
2. Description of the Related Art
Memory modules, such as single in-line memory modules and dual in-line memory modules typically contain multiple semiconductor memory devices. A single in-line memory module employs a single line of metal pins or contacts on one side of the module, and a dual in-line memory module employs two lines of metal pins or contacts on opposite sides of the module. Thus, a dual in-line memory module can accommodate a greater number of metal pins for electrical connection to an external system than a single in-line memory module of the same size. As the functions and structures of computer systems become more complicated and therefore require more contacts and I/O signals, dual in-line memory modules are being used more frequently than single in-line memory modules.
FIG. 1 shows a conventional dual in-line memory module 101, which includes a printed circuit board 111 on which a plurality of semiconductor memory devices (not shown) are mounted, Two pin blocks 121 and 122 are on printed circuit board 111 for electrically connecting the semiconductor memory devices to an external system. Each of pin blocks 121 and 122 includes a plurality of contact pins 131. In the conventional dual in-line memory module 101, the pitch between contact pins 131 must be reduced, or the printed circuit board 111 must be enlarged, to increase the number of pins 131. However, there is a limit to the reduction of the pitch of pins 131. Thus, to increase the number of pins 131, the size of the printed circuit board 111 must be increased.
FIG. 2 shows a conventional electronic component socket 211 mounted on a circuit board 221. Socket 211 has two pin blocks 231 and 232 with each of pin blocks 231 and 232 a set of metal pins 241. Pins 241 in socket 211 couple to matching pins 131 on dual in-line memory module 101 of FIG. 1 when dual in-line memory module 101 is plugged into socket 211. The semiconductor devices on module 101 electrically connect through pins 131 and 241 to a plurality of semiconductor devices (not shown) on circuit board 221.
In the conventional dual in-line memory module 101 as described above, increasing the number of pins 131 to accommodate the functionality of semiconductor memory devices mounted on dual in-line memory module 101 requires increasing the size of dual in-line memory module 101. A larger dual in-line memory module 101 requires a larger socket 211. Further, any system using dual in-line memory module 101 and electronic component socket 211 must be larger, and the manufacturing cost of the system is increased.
In accordance with an aspect of the present invention a multi in-line memory module has three or more lines of pins to increase the number of pins on a memory module without increasing the size of the memory module. Further, an accompanying socket for the multi in-line module can accommodate the larger number of pins without a corresponding increase in required system size. In accordance with an embodiment of the invention, a multi in-line module includes a printed circuit board having at least two protrusions formed along one edge. Each of the protrusions has two surfaces suitable for pin blocks, and one pin block is on each surface of the protrusions, although one of the surface can be unused if the module has sufficient pins without using the surface. For memory applications, semiconductor memory devices are mounted on at least one surface of the circuit board, and the pin blocks on the protrusions connect to the semiconductor memory devices via conductive paths inside the protrusions and/or the circuit. In an exemplary embodiment, each of the pin blocks includes a plurality of metal pins, and the surfaces of the protrusions are parallel to the surfaces of the circuit board.
In accordance with another embodiment of the invention, a multi in-line module includes: at least two printed circuit boards each having first and second surfaces. A fixing device connects the printed circuit boards as a single body. With one pin block formed on each surface of the printed circuit broad, the module provides more pins than does a conventional DIMM. Preferably, each of the pin blocks includes a plurality of metal pins, and the fixing device fixes the printed circuit boards parallel to each other. It is also preferable that semiconductor memory devices are mounted on at least one surface of at least one of the printed circuit boards.
In accordance with yet another embodiment of the invention, an electronic component socket includes at least three protrusions formed on a base and pin blocks formed on the side surfaces of the protrusions. Preferably, each of the pin blocks includes a plurality of metal pins. The base and the protrusions are typically dielectrics. The electronic component socket couples to a multi in-line memory module when a board or a protrusion of the module is in each of the gaps between the protrusions of the socket. The base of the socket is typically a printed circuit board on which devices that connect to the module are mounted.
According to an aspect of the present invention, the number of pins available to a memory module can be increased without a proportion increase in size of the memory module.